Semiconductor inspection system

ABSTRACT

An operator-free and fully automated semiconductor inspection system with high throughput is realized. All conditions required for capturing and inspection are generated from design information such as CAD data. In order to perform actual inspection under the conditions, a semiconductor inspection system is composed of a navigation system for generating all the conditions required for capturing and inspection from the design information and a scanning electron microscope system for actually performing capturing and inspection. Moreover, in the case of performing a matching process between designed data and a SEM image, deformed parts are corrected by use of edge information in accordance with multiple directions and smoothing thereof. Furthermore, a SEM image corresponding to a detected position is re-registered as a template, and the matching process is thereby performed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor inspection system foranalyzing patterns on a semiconductor wafer by use of design data. Morespecifically, the present invention relates to a semiconductorinspection system provided with a system configuration for automaticallygenerating conditions for capturing and inspection of patterns out ofthe design data, as well as a method of stably performing a matchingprocess between the design data and scanning electron microscope (SEM)images.

2. Background Art

In recent years, there is a production shift in the semiconductorindustry from production of memory chips to production of system largescale integrated circuits (LSIs). From a viewpoint of patterns on asemiconductor wafer, unlike patterns of a memory chip, patterns of asystem LSI are not designed as simply repeated patterns. Accordingly, inthe case of performing pattern measurement of the system LSI with alength-measuring SEM, which is one of the semiconductor evaluationsystems, templates for measuring positions, in other words, templatesfor matching need to be frequently changed. In actual measurement,frequent capturing operations for registration of the templates mayincur a considerable decline in entire throughput. Accordingly,generation of the templates directly from existing design data such ascomputer aided design (CAD) data has been requested. In the meantime, awafer size is increased up to 300 mm, whereby the wafer cannot beconveyed by manpower. In addition, inspection in a high-purity cleanroom is becoming essential. Therefore, complete robotization has beendesired in a semiconductor facility. Accordingly, an operator-free andfully-automated semiconductor inspection system is requested, which isnot arranged to generate only the templates for measuring positions butis also arranged to generate all conditions required for inspectionincluding capturing conditions, points for length measurement andlength-measuring algorithms out of the design data, whereby actualinspection is performed under the foregoing conditions.

In a conventional length-measuring SEM, an image of an actual wafer iscaptured first and the image is used for registration of the points forimage recognition, the positions for length measurement and thelength-measuring algorithms. In other words, the actual wafer isrequired in the first place, and it is also necessary to occupy thelength-measuring SEM temporarily to perform capturing of SEM images andregistration of various conditions. Moreover, since technologies formatching design data with SEM images have not been developed adequately,accurate matching has been difficult to do. For example, in the case ofspecifying a pattern position on a SEM image of a semiconductor wafer byapplying the design data to a template with the conventional technology,the SEM image is filtered with a Sobel filter or the like to detect edgecomponents for generating an edge image, and then matching such as anormalized correlation process between the edge image and the designdata is performed.

FIG. 1 shows a schematic flowchart of conventional processes and FIG. 7shows some image examples used in the conventional processes. First inStep 101, registration of a template of a desired pattern is performedby use of the design data. The pattern registered from the design datais shown as an image 701. Next, a SEM image is obtained in Step 102. Theobtained SEM image is shown as an image 702. In Step 103, the obtainedSEM image is subjected to edge emphasis filtering with a Sobel filter orthe like. In Step 104, the edge-emphasized image is converted intobinary codes for generating a line image in which the edge is onlyextracted. An image 703 shows the line image extracted out of the SEMimage 702. In Step 105, a matching process such as normalizedcorrelation is performed between the line image and the design imageregistered in Step 101. Then, position detection is performed in Step106. When detection is performed a plurality of times, Step 102 to 107will be iterated.

In a conventional semiconductor inspection system, registration ofpoints for image recognition, positions for length measurement andlength-measuring algorithms have been performed once after capturing animage of an actual wafer and by use of the image. For this reason, therehas been a problem that throughput is not improved because registrationis time-consuming and the system is occupied at the time ofregistration. Moreover, there has been a problem that it is impossibleto construct an operator-free and fully automated semiconductorinspection system because the conventional system always requires anoperator for judgment and registration by observation of actual SEMimages. Furthermore, concerning the technology for matching designinformation with the SEM images, the conventional technology cannotrespond to deformation between the CAD data and the SEM images. Theconventional technology also has a problem in the event of extractingedge information out of the SEM image that the edge information cannotbe adequately extracted due to a signal/noise ratio (an S/N ratio) ofthe image. In the event of generating a line image by conversion intobinary codes, the conventional technology would be incapable ofobtaining an optimum value for a threshold, because determinationthereof has been difficult. Accordingly, there has been a problem that acorrelation coefficient becomes considerably small in the subsequentmatching process by normalized correlation.

SUMMARY OF THE INVENTION

An object of the present invention is to realize an operator-free andfully-automated semiconductor inspection system which generates allnecessary conditions, including, conditions for capturing, points forlength measurement and length-measuring algorithms, out of designinformation such as CAD data for performing actual inspection underthose conditions. Another object of the present invention is to realizethe semiconductor inspection system capable of executing a stablematching process with a high correlation value in the case of performingthe matching process between the design data using as a template and SEMimages in that system.

In order to achieve the foregoing objects, a first aspect of the presentinvention is a semiconductor inspection system, which includes: anavigation system for storing design information such as CAD data of asemiconductor chip and for setting capturing and inspecting conditionsincluding a region on a semiconductor wafer subject to inspection basedon the design information; and a scanning electron microscope system forperforming actual capturing of the semiconductor wafer and for executinginspection in accordance with the capturing and inspecting conditionsbeing set up.

A second aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the navigation systemincludes a function to design semiconductor patterns by itself or afunction to retrieve the design information from another navigationsystem connected via a network, foregoing another navigation systempossessing a designing function.

A third aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the navigation systemspecifies and retrieves desired design data out of the stored designinformation to display the design data on a display screen.

A fourth aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the navigation systemincludes a function to specify and retrieve an arbitrary portion out ofthe CAD data being the stored design information and to generate bitmapdata therefrom.

A fifth aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the navigation system hasa function to effectuate automatic editing of all the capturing andinspecting conditions to be used in the scanning electron microscopesystem out of the design information including the CAD data and totransmit the edited capturing and inspecting conditions to the scanningelectron microscope system.

A sixth aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the navigation system hasa function to effectuate transmission and receipt of data with anothernavigation system connected to a network of a facility installed andfurther to transmit the capturing and inspecting conditions to aplurality of the scanning electron microscope systems connected to thenetwork.

A seventh aspect of the present invention is the semiconductorinspection system according to the first aspect, in which the navigationsystem includes: a bitmap data generator having a function to generatebitmap data by retrieving desired design data out of the stored designinformation; and a capturing and inspecting condition editor having afunction to edit and transmit the capturing and inspecting conditions tobe used in the scanning electron microscope system out of the designdata.

An eighth aspect of the present invention is the semiconductorinspection system according to the first aspect, in which the navigationsystem has a function to automatically detect a characteristic patternportion and to register the pattern portion as a template, in the caseof selecting a template for matching out of bitmap data as one of theinspecting conditions to be used in the scanning electron microscopesystem.

A ninth aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the scanning electronmicroscope system uses the capturing and inspecting conditions receivedfrom the navigation system, obtains a scanning electron microscope imageautomatically and performs inspection.

A tenth aspect of the present invention is the semiconductor inspectionsystem according to the first aspect, in which the scanning electronmicroscope system uses the capturing and inspecting conditions receivedfrom another navigation system connected via a network, obtains ascanning electron microscope image automatically and performsinspection.

An eleventh aspect of the present invention is the semiconductorinspection system according to the first aspect, in which the scanningelectron microscope system has a function for matching between bitmapdata generated from the design information and a scanning electronmicroscope image.

A twelfth aspect of the present invention is the semiconductorinspection system according to the eleventh aspect, in which thescanning electron microscope system includes: means for generating edgeimages by retrieving edge information severally from the scanningelectron microscope image obtained by capturing and from a templatebeing bitmap data in the case performing a matching process with thescanning electron microscope image obtained by capturing using thebitmap data from the design data as a template; and means for performingthe matching process with respect to the edge images severally generatedfrom the scanning electron microscope image and the template whileproviding the both images with a smoothing process severally so as tomake up deformed parts of the both images.

A thirteenth aspect of the present invention is the semiconductorinspection system according to the eleventh aspect, in which thescanning electron microscope system retrieves edge information inaccordance with multiple directions and generates edge images dependingon the multiple directions in the case of generating edge images byretrieving edge information from a scanning electron microscope imageand from a template being bitmap data, and the scanning electronmicroscope system performs a matching process with respect to each ofthe images.

A fourteenth aspect of the present invention is the semiconductorinspection system according to the eleventh aspect, in which thescanning electron microscope system performs a matching process bycomposing edge images generated in accordance with multiple directionsand by integrating the edge images into one image, in the case ofgenerating edge images by retrieving edge information from a scanningelectron microscope image and from a template being bitmap data.

A fifteenth aspect of the present invention is the semiconductorinspection system according to the first aspect, in which the scanningelectron microscope system includes: means for generating an edge imageby retrieving edge information from a scanning electron microscope imageobtained by capturing in the case of performing a matching processbetween the scanning electron microscope image and bitmap data from thedesign information as a template; means for re-registering a portion ofthe scanning electron microscope image as a template, foregoing portioncorresponding to a position of the edge image detected by the matchingprocess between the edge image and design data; and means for using there-registered template of the scanning electron microscope image in thesubsequent matching process.

A sixteenth aspect of the present invention is the semiconductorinspection system according to the fifteenth aspect, in which thescanning electron microscope system carries out re-registration of thetemplate during repeated capturing processes at an interval of anarbitrary period of time or an arbitrary frequency of the processes inthe case that the scanning electron microscope system uses there-registered template of the scanning electron microscope image andperforms the matching processes with respect to scanning electronmicroscope images repeatedly captured.

A seventeenth aspect of the present invention is the semiconductorinspection system according to the fifteenth aspect, in which thescanning electron microscope system compares a correlation value betweenthe design data and the scanning electron microscope image every timeand re-registers a new template only when the compared correlation valueis higher than the correlation value of the template used at that time.

An eighteenth aspect of the present invention is the semiconductorinspection system according to the fifteenth aspect, in which thescanning electron microscope system performs an arbitrary frequency ofthe matching processes initially, compares correlation values betweenthe design data and the scanning electron microscope images obtained inthe arbitrary frequency of the matching processes, and re-registers thescanning electron microscope image having the highest correlation valueas a new template.

A nineteenth aspect of the present invention is the semiconductorinspection system according to the first aspect, in which the capturingand inspecting conditions are selected from a capturing and inspectingcondition file registered in advance with any one of the navigationsystem and the scanning electron microscope system.

A twentieth aspect of the present invention is the semiconductorinspection system according to the nineteenth aspect, in which thecapturing and inspecting conditions are selected from the capturing andinspecting condition file weighted in accordance with a frequency of usein the past.

A twenty-first aspect of the present invention is the semiconductorinspection system according to the nineteenth aspect, in which acapturing and inspecting condition inside the capturing and inspectingcondition file is automatically deleted from the capturing and deletingcondition file when a frequency of use of the capturing and inspectingcondition is lower than a predetermined frequency.

A twenty-second aspect of the present invention is the semiconductorinspection system according to the nineteenth aspect, which furtherincludes a function to modify and to edit a part of the capturing andinspecting conditions inside the capturing and inspecting conditionfile, the capturing and inspecting condition file being registered inadvance.

A twenty-third aspect of the present invention is the semiconductorinspection system according to the nineteenth aspect, which furtherincludes a function to register a condition with the capturing andinspecting condition file as another condition, when a part of thecapturing and inspecting conditions inside the capturing and inspectingcondition file being registered in advance is modified.

The semiconductor inspection system according to the first aspect iscomposed of the navigation system for storing the design data of asemiconductor chip and the scanning electron microscope system forexecuting actual capturing and inspection of a semiconductor wafer byuse of the information. Therefore, it is possible to construct a systemwhich generates the capturing and inspecting conditions using the designdata of a semiconductor chip and actually executes capturing andinspection.

In the semiconductor inspection system according to the second aspect,the navigation system includes the function to design semiconductorpatterns by itself or the function to retrieve and store the designinformation from another navigation system connected via a network whichpossesses a designing function. Therefore, the capturing and inspectingconditions can be readily set up based on the design information.

In the semiconductor inspection system according to the third aspect,the navigation system is provided with a function to specify andretrieve desired design data out of the design information storingvarious information such as layers and cells required for patterndesigning and to display the design data on a display screen. Therefore,an operator can readily set up the capturing and inspecting conditionsbased on the design data on the display screen.

In the semiconductor inspection system according to the fourth aspect,the navigation system is provided with the function to retrieve anarbitrarily specified portion out of the CAD data being the designinformation in order to generate bitmap data. Therefore, the bitmap datacan be used for matching by the scanning electron microscope system.

In the semiconductor inspection system according to the fifth aspect,the navigation system is provided with the function to effectuateautomatic editing of all the capturing and inspecting conditions to beused in the scanning electron microscope system out of the designinformation including the CAD data and to transmit the edited capturingand inspecting conditions to the scanning electron microscope system.Therefore, the scanning electron microscope system can execute capturingand inspection by use of the automatically extracted conditions, wherebyfull-automation of the system becomes feasible.

In the semiconductor inspection system according to the sixth aspect,the navigation system is provided with the function to effectuatetransmission and receipt of data with another navigation systemconnected to a network of a facility installed and further to transmitthe capturing and inspecting conditions to a plurality of the scanningelectron microscope systems connected to the network. Therefore, aplurality of navigation systems and a plurality of the scanning electronmicroscope systems can collaborate to execute efficient capturing andinspection.

In the semiconductor inspection system according to the seventh aspect,the navigation system includes a portion having the function to generatebitmap data by retrieving desired design data out of the stored designinformation, and a portion having the function to edit and transmit thecapturing and inspecting conditions to be used in the scanning electronmicroscope system out of the design data. Therefore, the capturing andinspecting conditions can be edited by use of the bitmap data. Moreover,the navigation system can be also composed of a plurality of systems byuse of the network.

In the semiconductor inspection system according to the eighth aspect,the navigation system is provided with the function to automaticallydetect a characteristic pattern portion and to register the patternportion as a template, in the case of selecting a template for matchingout of bitmap data as one inspecting condition to be used in thescanning electron microscope system. Therefore, the templateregistration does not require manpower.

In the semiconductor inspection system according to the ninth aspect,the scanning electron microscope system is provided with the function touse the capturing and inspecting conditions received from the navigationsystem, to obtain a scanning electron microscope image automatically andto perform inspection. Therefore, the system does not require control byan operator and capturing and inspection can be thereby automated.

In the semiconductor inspection system according to the tenth aspect,the scanning electron microscope system is provided with the function touse the capturing and inspecting conditions received from anothernavigation system connected via a network, to obtain a scanning electronmicroscope image automatically and to perform inspection. Therefore, aplurality of scanning electron microscope systems can be automaticallyoperated without controlling by an operator.

In the semiconductor inspection system according to the eleventh aspect,the scanning electron microscope system is provided with the functionfor matching between bitmap data generated from the design informationand a scanning electron microscope image. Therefore, the scanningelectron microscope system can perform highly accurate and efficientinspection by use of the design information.

In the semiconductor inspection system according to the twelfth aspect,the scanning electron microscope system is provided with a function togenerate edge images by retrieving edge information severally from thescanning electron microscope image obtained by capturing and from atemplate being bitmap data in the case of performing a matching processbetween the scanning electron microscope image and the bitmap data outof the design data while providing a smoothing process severally so asto make up deformed parts thereof. Therefore, matching can be performedwith a high detection ratio.

In the semiconductor inspection system according to the thirteenthaspect, the scanning electron microscope system is provided with afunction to retrieve edge information in accordance with multipledirections and to generate edge images depending on the multipledirections in the case of generating edge images by retrieving edgeinformation from a scanning electron microscope image and from thebitmap data, a function to perform a matching process with respect toeach of the images. Therefore, matching can be performed with goodpositional accuracy.

In the semiconductor inspection system according to the fourteenthaspect, the scanning electron microscope system is provided with afunction to perform a matching process by composing edge imagesgenerated in accordance with multiple directions and by integrating theedge images into one image in the case of generating edge images byretrieving edge information from a scanning electron microscope imageand from bitmap data. Therefore, matching can be performed with finepositional accuracy and in a high speed.

The semiconductor inspection system according to the fifteenth aspectuses the re-registered template of the SEM image and effectuates amatching process between graded SEM images. Therefore, matching can beperformed with a high correlation value and with a stable detectionratio.

In the semiconductor inspection system according to the sixteenthaspect, re-registration of the template as described in the fifteenthaspect is carried out during repeated capturing at an interval of eitheran arbitrary period of time or an arbitrary frequency of the processes.Therefore, the matching process with a high correlation value and with astable detection ratio can be performed in response to changes of SEMimages with passage of time in the course of capturing.

In the semiconductor inspection system according to the seventeenthaspect, a correlation value between the design data and a SEM image iscompared in the case of registering a new template, and the template isre-registered only when the correlation value is higher than before.Therefore, the template can be optimized along with a higher correlationvalue.

In the semiconductor inspection system according to the eighteenthaspect, the matching processes between the design data and the edgeimages as described in the fifteenth aspect are performed initially inan arbitrary frequency. Thereafter, correlation values then are comparedand the edge image having the highest correlation value of all the edgeimages is re-registered as the template. Accordingly, it is possible toselect a template of a SEM image having a higher correlation value.

In the semiconductor inspection system according to the nineteenthaspect, either the navigation system or the scanning electron microscopesystem is provided with a function to select the capturing andinspecting conditions from a previously registered file. Therefore, theconditions can be efficiently decided.

In the semiconductor inspection system according to the twentiethaspect, in the case of selecting from the capturing and inspectingcondition file, the capturing and inspecting conditions are weighteddepending on a frequency of use in the past and the conditions areselected therefrom. Therefore, the conditions can be efficientlydecided.

In the semiconductor inspection system according to the twenty-firstaspect, a capturing and inspecting condition inside the capturing andinspecting condition file is deleted automatically from the capturingand inspecting condition file in the case that a frequency of usethereof is lower than a predetermined frequency. Therefore, theconditions can be efficiently decided.

In the semiconductor inspection system according to the twenty-secondaspect, the semiconductor inspection system of the nineteenth aspect isprovided with a function to modify and edit a part of the capturing andinspecting conditions inside the capturing and inspecting condition fileregistered in advance. Therefore, the conditions can be efficientlydecided with reference to the precedent conditions.

In the semiconductor inspection system according to the twenty-thirdaspect, in the case that a part of the capturing and inspectingconditions inside the capturing and inspecting condition file beingregistered in advance is modified and edited, the semiconductorinspection system of the nineteenth aspect is provided with a functionto register the relevant condition with the capturing and inspectingcondition file as another condition. Therefore the conditions can beefficiently decided thereafter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a flowchart of a conventional matching process between designdata and a SEM image.

FIG. 2 is a flowchart of a matching process by use of design data and aSEM image according to one embodiment of the present invention.

FIG. 3 is a schematic diagram of a configuration of a semiconductorinspection system according to the embodiment of the present invention.

FIG. 4 is a flowchart for a case of time-lapse re-registration of a SEMimage as a template according to the embodiment of the presentinvention.

FIG. 5 is a flowchart of a re-registration process of a SEM image as atemplate according to the embodiment of the present invention, in thecase that a correlation value is higher than the previous value.

FIG. 6 is a flowchart of a re-registration process of a SEM image as atemplate according to the embodiment of the present invention, in whichthe SEM image having the highest correlation value during an arbitraryfrequency of the matching processes between the design data and the SEMimages is re-registered.

FIG. 7 shows image examples used in a conventional process.

FIG. 8 is a flowchart of a matching process by use of a template ofbitmap data and a SEM image according to the embodiment of the presentinvention.

FIG. 9 is a flowchart of a matching process by use of a template ofbitmap data and a SEM image according to another embodiment of thepresent invention.

FIG. 10 shows a method of composition and integration of an imagedecomposed into directions.

FIG. 11 is a view of a configuration of a semiconductor inspectionsystem according to the embodiment of the present invention.

FIG. 12 is a view of a configuration of a navigation system according tothe embodiment of the present invention.

FIG. 13 is a view of a configuration of the semiconductor inspectionsystem according to another embodiment of the present invention.

FIG. 14 is a view of a network configuration of the semiconductorinspection system according to the embodiment of the present invention.

FIG. 15 is a display example in the navigation system according to theembodiment of the present invention.

FIG. 16 is an example of bitmap data generated by the navigation systemaccording to the embodiment of the present invention.

FIG. 17 is a flowchart of a process performed by the navigation systemaccording to the embodiment of the present invention.

FIG. 18 shows examples of specifying a length-measuring point and atemplate in the navigation system according to the embodiment of thepresent invention.

FIG. 19 is a flowchart of a process performed by a scanning electronmicroscope system according to the embodiment of the present invention.

FIG. 20 shows an automatic condition file according to the embodiment ofthe present invention, in which capturing and inspecting conditions areregistered.

FIG. 21 is a flowchart of a process in the case of using the automaticcondition film according to the embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 3 is a block diagram of a schematic configuration of a scanningelectron microscope system of the present invention. Reference numeral301 denotes a body of an electron microscope. An electron beam 303emitted out of an electron gun 302 is converged by an unillustratedelectron lens and irradiated on a sample 305. Either intensity ofsecondary electrons generated from a surface of the sample or intensityof reflected electrons by electron beam irradiation is detected by anelectron detector 306 and amplified by an amplifier 307. Referencenumeral 304 denotes a deflector 304 which deflects the electron beam,thus subjecting the electron beam 303 to raster scanning on the samplesurface according to a control signal 308 of a controlling computer 310.A signal outputted from the amplifier 307 is converted from analog todigital inside an imaging processor 309, whereby digital image data aregenerated. Reference numeral 311 denotes a display device for displayingthe image data. Moreover, the imaging processor 309 includes an imagememory for storing the digital image data, an imaging circuit forperforming various imaging processes and a display control circuit forperforming display control. Input means 312 such as a keyboard and amouse is connected with the controlling computer 310.

During fabrication of a semiconductor device, the electron microscopesystem is used upon measurement of line widths of fine patterns drawn ona wafer. In this event, the normalized correlation method is currentlyused as a method to find out a portion on the wafer to measure the linewidth. In such a case, selection of an optimum template is deemedessential. The imaging processor 309 of the present invention has aconstitution which effectuates optimum template selection upon templatematching, whereby the imaging processor 309 is adoptable to the electronmicroscope system.

FIG. 2 is a flowchart of a matching process according to one embodimentof the present invention using design data and a SEM image. First inStep 201, a pattern portion requested for detection is registered out ofthe design data as a template. The SEM image is obtained in Step 202,and the matching process is performed in Step 203. Although there arevarious ways concerning this matching process, a way similar to Steps103 to 105 of FIG. 1 (the edge emphasis filtering process, the binaryconversion process and the normalized correlation process) may be used,for example. As a result, a position on the SEM image corresponding tothe pattern of the designed data is detected in Step 204. Next in Step205, the portion of the SEM image detected in Step 204 as correspondingto the pattern of the design data is re-registered as a template.Thereafter, another SEM image is obtained in Step 206. Then in Step 207,a matching process is performed while using the SEM image re-registeredin Step 205 as the template, and position detection is performed in Step208. In the foregoing steps, since the re-registered template is a SEMimage, the matching process takes place between two graded SEM images.Accordingly, it is possible to perform the matching process with a highcorrelation value and a stable detection ratio as well. When detectionis performed a plurality of times, Steps 206 to 209 will be iterated. Ifthe template for initial registration is preset, then the subsequentprocesses can be conducted automatically by a computer program.

FIG. 4 is a flowchart of a case of time-lapse re-registration of the SEMimage as the template according to the embodiment of the presentinvention. Steps 401 to 408 correspond to Steps 201 to 208 of FIG. 2,respectively. In Step 409, judgment is made as to whether or notre-registration of the template is carried out in every certain timeinterval or in every certain process frequency. When re-registration iscarried out, Steps 402 to 405 are executed for performing the matchingprocess again by use of the design data and the SEM image. In this way,it is possible to perform the matching process with a high correlationvalue and a high detection ratio even if the SEM image is changed withpassage of time in the course of image capturing.

FIG. 5 is a flowchart of a re-registration process of the SEM image asthe template according to the embodiment of the present invention, inthe case that the correlation value higher than the previous value isobtained. Steps 501 to 504 and Steps 506 to 510 correspond to Steps 401to 404 and Steps 405 to 409 of FIG. 4, respectively. In Step 510,judgment is made as to whether or not re-registration of the template iscarried out in every certain time interval or in every certain processfrequency. When re-registration is carried out, Steps 502 to 504 areexecuted for performing the matching process again by use of the designdata and the SEM image. Next in Step 505, if the correlation valuedetected in the position at this time is higher than the correlationvalue of the currently effective template, re-registration of thetemplate is performed in Step 506. However, if the detected correlationvalue is smaller than the correlation value of the currently effectivetemplate, re-registration does not take place and the process proceedsto subsequent Steps starting from Step 507. Accordingly, it is possibleto optimize the template for use as the template having the highestcorrelation value.

FIG. 6 is a flowchart of a re-registration process of the SEM image asthe template according to the embodiment of the present invention, inthe case which the matching processes between the design data and theSEM image are performed in an arbitrary frequency, whereby the SEM imagein the position highest in the correlation value among all thecorrelation values of the SEM images is re-registered as the template.Steps 601 to 604 and Steps 606 to 610 correspond to Steps 201 to 204 andSteps 205 to 209 in FIG. 2, respectively. The matching processes usingthe design data and the SEM image are iterated by an arbitrary frequencyfrom Step 602 to Step 605, and then in Step 606, the SEM image in theposition highest in the correlation value among all the detectedpositions is re-registered as the template. Accordingly, it is possibleto select the SEM image high in the correlation value. When detection isperformed a plurality of times, Steps 607 to 609 will be iterated by useof the template. Note that the both processes shown in FIG. 4 and inFIG. 6 can be automated by computer programs.

FIG. 8 is a flowchart of the matching process according to theembodiment of the present invention by use of a template of bitmap dataand the SEM image. In Step 801, edge information is severally extractedout of the bitmap data and out of the SEM image. In this part of theprocess, an edge emphasis filter such as a Sobel filter is generallyused. In this part, both images lose contrast information and matchingis thereby facilitated. However, since the SEM image has quite adifferent shape from the actual CAD data, the detection ratio uponmatching will be reduced if nothing is done. Therefore, in Step 802,each of both images converted into edge images is severally subjected toa smoothing process to make up deformation thereof. A slightly strongersmoothing filter is applied this part of the process. In addition,smoothing strength should be varied according to the CAD data or the SEMimage; specifically, smoothing of the CAD data should be carried outmore strongly. Since the pair of edge images, of which deformed partsare corrected, are subjected to the matching process in Step 803, it ispossible to perform the matching process with a high detection ratio.Note that the matching process can be automated by a computer program ifthe edge information is preset severally by the bitmap data and the SEMimage to be initially extracted.

FIG. 9 is a flowchart of the matching process according to anotherembodiment of the present invention by use of the template of bitmapdata and the SEM image. A difference from the process flow of FIG. 8 isthat edge extraction is performed in multiple directions in Step 901. Asfor edge extraction process in multiple directions, generally used is aSobel filter which is capable of extracting edges in multipledirections. As for the directions, either 2 directions of X and Y, or 4directions of X, Y, XY and YX is used. In Step 902, a smoothing processis performed on each edge image decomposed in each direction in order tomake up a deformed part thereof. In Step 903, images decomposed in therespective directions are composed and integrated as illustrated in FIG.10. In Step 904, the matching process can be performed between a pair ofplain images owing to the above composition process. Needless to say,the matching process may be also performed severally with respect toeach pair in the corresponding direction without performing theintegration in Step 903. By extracting the edges and subjecting to thematching process with respect to each direction, matching accuracy ineach direction can be enhanced. Note that an original image in FIG. 10corresponds to a template and to an inputted SEM image in FIG. 9.Accordingly, upon finding differentials of these images in the Xdirection, such differentiation is carried out by dividing the originalimages into a plurality of lines along the Y direction. On the contrary,upon finding differentials in the Y direction, such differentiation iscarried out by dividing the original images into a plurality of linesalong the X direction. This matching process can be also automated by acomputer program.

FIG. 11 is a view of a configuration of a semiconductor inspectionsystem according to the embodiment of the present invention. Referencenumeral 1101 denotes a navigation system, which is capable of storingdesign information of a semiconductor chip such as CAD data, andarbitrarily retrieving regions for inspection out of the designinformation. Reference numeral 1102 denotes the scanning electronmicroscope system for actually performing image capturing of asemiconductor wafer by using the information, and for executing giveninspection. These systems 1101 and 1102 are linked together with anetwork, thus having a configuration to effectuate exchanges ofinformation and data.

FIG. 12 is a view of a configuration of the navigation system accordingto the embodiment of the present invention. The navigation system 1101is composed of a bitmap data generator 1201 having functions to retrievedesired design data out of the stored design information and to generatebitmap data therefrom, and a capturing and inspecting condition editor1202 having a function to edit and transmit capturing and inspectingconditions out of the design data for use in the scanning electronmicroscope system 1102. In the meantime, the navigation system 1101 maybe composed in a manner that functional parts of the bitmap datagenerator 1201 and the capturing/editing condition editor 1202 areseparately configured within one workstation (a WS) or one personalcomputer (a PC), or in a manner that the functional parts thereof areseparately configured in two or a plurality of WSs or PCs.

FIG. 13 is a view of a configuration of the semiconductor inspectionsystem according to another embodiment of the present invention. Anavigation system 1302 possesses a designing function of semiconductorpatterns by itself. If the navigation system 1302 does not possess thedesigning function, the navigation system 1302 retrieves the designinformation from another system 1301 having the designing function,which is connected via the network, and uses the information.

FIG. 14 is a view of a network configuration of the semiconductorinspection system according to the embodiment of the present invention.In the semiconductor inspection system of the present invention, anavigation system 1401 can transmit and receive data with othernavigation systems 1402 to 1404 connected to a network of a facilityinstalled. The navigation system 1401 can further transmit the capturingand inspecting conditions to a plurality of scanning electron microscopesystems 1405 and 1406 connected to the network. In this way, it ispossible to share the capturing and inspecting conditions within thenetwork, and it is also possible to drive a plurality of systemsautomatically and simultaneously.

FIG. 15 is a display example in the navigation system according to theembodiment of the present invention. Design data 1501 of a semiconductoris stored in the navigation system, and the navigation system has afunction to allow an operator to retrieve a specified portion 1502 outof the design data 1501 by specifically inputting the design informationsuch as layers and cells with respect to the specified portion 1502 inorder to display the specified portion 1502 on a display screen as shownin reference numeral 1503. In this case, the design data 1501 may bestored in another design system connected via the network as shown inFIG. 13.

FIG. 16 is an example of the bitmap data generated by the navigationsystem 1302 according to the embodiment of the present invention.Reference numeral 1601 denotes a region retrieved from the design datain FIG. 15. Within this region, a portion 1602 subject to inspection andlength measurement is specified. In this case, such aninspection/length-measurement specified region 1602 is converted intobitmap data 1603 and then transmitted to the scanning electronmicroscope system 1303. Here, the bitmap data 1603 consists of twovalues of black and white. However, such colors may be set uparbitrarily.

FIG. 17 is a flowchart of a process performed by the navigation systemaccording to the embodiment of the present invention. In Step 1701,layer and cell information of the design or the like is specified asshown in FIG. 15, whereby the data specified out of the stored designdata are displayed on the screen. A region for capturing is specified inStep 1702. In Step 1703, pattern data and positional information withina scope (the region specified as the region for capturing) are retrievedand then converted into the bitmap data 1603. This part is the same asthe content as shown in FIG. 16. Next in Step 1704, a place subject toinspection and length measurement is specified and coordinate datathereof are read in. In Step 1705, specification of a template formatching is performed and registration of pattern data and positionalinformation of the template are performed. As for specification of thetemplate, the operator normally selects and specifies the mostdistinctive and characteristic portion. It is also possible to specifysuch a characteristic portion automatically by use of an imageprocessing technology to detect high frequency components anddistinction of an image. Lastly in Step 1706, all the informationnecessary for performing capturing and inspection with the scanningelectron microscope system is edited based on the information gatheredin Steps 1701 to 1705, and the edited information is transmitted to thescanning electron microscope system.

FIG. 18 shows examples of specifying a length-measuring point and thetemplate in the navigation system according to the embodiment of thepresent invention. Reference numeral 1801 denotes specification of thelength-measuring point and reference numeral 1802 denotes specificationof the template. Although the image subject to specification herein isset as bitmap data, it is by all means possible to specify the templateon the design data prior to conversion into the bitmap data.

FIG. 19 is a flowchart of a process performed by the scanning electronmicroscope system according to the embodiment of the present invention.In Steps 1901 to 1904, information concerning wafer alignment,information concerning the template for matching and informationconcerning the length-measuring point, conditions for capturing and amethod of length measurement are registered based on the informationtransmitted in Step 1706 of FIG. 17. Actual capturing takes place inStep 1905. Then in Step 1906, a search process (detection of positions)is executed by use of the template registered in Step 1902. In Step1907, the length-measuring point is computed from matching coordinatesdetected in Step 1906 and length measurement is executed. In Step 1908,judgment is made as to whether or not length measurement is completedwith respect to all the length-measuring points. Step 1908 is providedfor effectuating length measurement with respect to all thelength-measuring points.

FIG. 20 shows an automatic condition file according to the embodiment ofthe present invention, in which capturing and inspecting conditions areregistered. The automatic condition file may reside either in thenavigation system or in the scanning electron microscope system. Actualcapturing and inspection are performed by the scanning electronmicroscope system in accordance with the conditions registered in theautomatic condition file 2001. In the case of deciding the capturing andinspecting conditions out of the information obtained by the navigationsystem, if the most suitable condition is selected from recipesregistered in advance as in the present invention, a process forgenerating the conditions can be simplified and management andmaintenance thereof become convenient. Moreover, each recipe registeredin the automatic condition file can be partially modified or deleted asillustrated in a table 2002. Furthermore, each recipe can be alsoregistered in another name. In addition, it is also possible to takestatistics as to how often each recipe is used in order to delete lessfrequently used recipes automatically.

FIG. 21 is a flowchart of a process in the case of using the automaticcondition film according to the embodiment of the present invention. InStep 2101, judgment is made as to whether a new recipe should begenerated or not. If an identical or partially modifiable recipe doesnot exist yet in the automatic condition file 2001, the new recipe isgenerated in Step 2102. After generated, the new recipe is registeredwith the automatic condition file 2001 in Step 2106. After registration,it is possible to execute the recipe in Step 2108 with referencethereto. There may be also a case where execution only takes placewithout registration. In the case that the identical or partiallymodifiable recipe already exists in the automatic condition file 2001,the existing recipe inside the automatic condition file is referred inStep 2103, and then judgment is made as to whether the recipe should bepartially modified or not in Step 2104. It is unnecessary to modify therecipe partially if the recipe is identical; therefore, the existingrecipe is executed directly in Step 2108. The same is applicable to acase in which the existing recipe is not identical but substitutable.When the recipe is to be partially modified, after partial modificationin Step 2105, judgment is made as to whether or not the modified recipeshould be registered with the automatic condition file 2001 in Step2106. Thereafter, the modified recipe is either registered in Step 2107then executed in Step 2108, or just executed in Step 2108 withoutregistration. By registering the recipe once used with the automaticcondition file, it is possible to refer to the condition next time.Moreover, if the capturing and inspecting condition is modifiedpartially, it is possible to register the modified condition as anothercondition in Step 2106. In this case, it is possible to refer to bothfiles before and after such modification.

As the present invention has the configuration as described above, thefollowing effects are achieved.

In a conventional semiconductor inspection system, registration ofpoints for image recognition, positions for length measurement andlength measuring algorithms has been performed once after capturing animage of an actual wafer and by use of the image. For this reason, therehas been a problem that throughput is not improved because theregistrations are time-consuming and the apparatus is occupied at thetime of the registrations. Moreover, there has been a problem that it isimpossible to construct an operator-free and fully-automatedsemiconductor inspection system because the conventional system alwaysrequires an operator for judgment and registration who observes actualSEM images.

In response to these problems, the present invention is arranged togenerate all conditions necessary for inspection, including, theconditions for capturing, the points for length measurement and thelength-measuring algorithms, out of the design information such as theCAD data. As the present invention is designed to perform actualinspection under these conditions, an operator-free and fully automatedsemiconductor inspection system with high throughput can be realized.

Moreover, in the conventional case of performing the matching processbetween the design data and the SEM images, it has been impossible toperform a stable matching process because the correlation efficientbecomes considerably small due to inadaptability to deformed partsbetween the design data and the SEM images. In response to the foregoingproblem, the present invention performs the matching process to make upthe deformed parts by use of the edge information in multiple directionsand smoothing thereof in the case that the matching process between thedesign data and the SEM images takes place. In addition, the presentinvention performs the matching process between the edge images and thetemplates of the design data, and performs the matching process afterre-registering the part of the SEM image corresponding to the detectedposition as the template. Therefore, a stable matching process with ahigh correlation value and a high detection ratio can be achieved.

1. A semiconductor inspection system, comprising: a navigation systemfor storing design information such as CAD data of a semiconductor chipand for setting capturing and inspecting conditions including a regionon a semiconductor wafer subject to inspection based on the designinformation; and a scanning electron microscope system for performingactual capturing of the semiconductor wafer and for executing inspectionin accordance with the capturing and inspecting conditions being set up.2-23. (canceled)